The present invention relates to an implantable drug delivery device for infusing a therapeutic agent into an organism, and more particularly, relates to a drug delivery device with a peristaltic implantable pump having an improved construction for installation of a drug delivery tube to the pump.
Implantable drug infusion devices are well known in the art. These devices typically include a medication reservoir within a generally cylindrical housing. Some form of fluid flow control is also provided to control or regulate the flow of fluid medication from the reservoir to the outlet of the device for delivery of the medication to the desired location in a body, usually through a catheter. These devices are used to provide patients with a prolonged dosage or infusion of a drug or other therapeutic agent.
Active drug infusion devices feature a pump or a metering system to deliver the drug into the system of a patient. An example of such a drug infusion pump currently available is the Medtronic SynchroMed programmable pump. Additionally, U.S. Pat. Nos. 4,692,147 (Duggan), 5,840,069 (Robinson), and 6,036,459 (Robinson), assigned to Medtronic, Inc., Minneapolis, Minn., disclose body-implantable electronic drug administration devices comprising a peristaltic (roller) pump for metering a measured amount of drug in response to an electronic pulse generated by control circuitry associated within the device. Each of these patents is incorporated herein by reference in their entirety for all purposes. Such devices typically include a drug reservoir, a fill port, a peristaltic pump having a motor and a pumphead to pump out the drug from the reservoir, and a catheter port to transport the drug from the reservoir via the pump to a patient""s anatomy. The drug reservoir, fill port, peristaltic pump, and catheter port are generally held in a housing, or bulkhead. The bulkhead typically has a series of passages extending from the drug reservoir and through the peristaltic pump that lead to the catheter port, which is typically located on the side of the housing. The peristaltic pump comprises a pumphead having rollers, a race or cavity defined by the bulkhead, and a pump tube that is threaded or inserted between the rollers and the race. The peristaltic pumps use the rollers to move a drug through the pump tube from the drug reservoir to the catheter port. The drug is then pushed by the pump through a catheter connected to the catheter port, and is delivered to a targeted patient site from a distal end of the catheter.
In the assembly or fabrication of peristaltic pumps, the pump tube must be installed in the device. More specifically, the pump tube must be threaded or inserted between the pump rollers and a race, and this installation is typically done as the pumphead is rotated. In conventional peristaltic pumps, the pump rollers can impede the installation of the pump tube between the rollers and the race. Impeding the insertion of the pump tube between the rollers and the race can increase manufacturing costs, and decrease ease and flexibility of manufacturing, as well as give rise to the potential for excessive load and/or damage to the pump tube during installation between the rollers and the race. It is an object of the present invention to provide an implantable drug infusion device which reduces or eliminates some or all of the difficulties in conventional devices and their manufacture.
It is an object of the present invention to provide an implantable drug infusion device which reduces or wholly overcomes some or all of the difficulties inherent in prior known devices. Particular objects and advantages of the invention will be apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this field of technology, in view of the following disclosure of the invention and detailed description of preferred embodiments.
The present invention provides an implantable drug infusion or delivery device which features a peristaltic pump having a new configuration, incorporating at least one retracting roller to provide for easier installation of the pump tube between the roller and the race during manufacture of the device.
In accordance with one aspect, an implantable drug infusion device includes a bulkhead having a race. A pump tube having an inlet and an outlet is positioned within the race, the race configured to support the tube along a path. A roller assembly is configured to compress the tube against the race at one or more points along the path, and the roller assembly includes a hub and at least one roller biased against the pump tube. A drive assembly drives the roller assembly relative to the pump tube along the path so as to move a liquid through the pump tube. The roller assembly has at least one retracting roller operably connected to the hub and/or to at least one adjacent roller to permit retraction of the roller during installation of the pump tube between the roller and the race.
In accordance with another aspect, the roller assembly includes at least one retracting roller operably connected to a retracting roller arm or roller housing. The roller assembly is designed so that the retracting roller can be retracted during fabrication of the device. In a preferred embodiment, the roller assembly includes at least one biasing member or spring operably connected to the retracting roller to bias the roller against the pump tube after installation of the pump tube between the roller and the race. Further, the biasing member can be compressed when the retracting roller arm is retracted from the race so that the space between the roller and the race is increased to provide for reduced impedance of travel of the pump tube between the roller and the race. Reduced impedance to travel of the pump tube is particularly desirable during the threading or insertion of the pump tube between the roller and the race during device manufacture. Still further, the retracting roller can be returned to or substantially close to its initial position prior to retraction and installation of the pump tube between the roller and the race.
In a preferred embodiment of the invention, the biasing member, such as a spring, is operably applied to at least one retracting roller arm or roller of the peristaltic pump. In another preferred embodiment, the peristaltic pump has more than one retracting roller and corresponding retracting roller arm or roller housing and biasing member operably connected thereto.
In accordance with yet another aspect, an implantable drug infusion device includes a bulkhead having a race, a first chamber, and a second chamber. A pump tube has an inlet and an outlet and is positioned within the race. A motor assembly is positioned within the first chamber, a pumphead assembly is positioned within the second chamber, and the motor assembly drives the pumphead assembly. The pumphead assembly includes a roller assembly having a hub (or base) and three retracting roller arms. Each retracting roller arm has a roller and is pivotally connected to the hub. A drive assembly drives the roller assembly relative to the tube along the path so the rollers compress the tube to move a liquid through the tube. A biasing member or spring is operably connected to each retracting roller arm, which can be compressed to an amount sufficient to retract the roller arm as may be desired during installation of the pump tube between the roller and the race. Further, the spring can bias the corresponding roller against the pump tube during normal operation of the device.
From the foregoing disclosure, it will be readily apparent to those skilled in the art, that is, those who are knowledgeable or experienced in this area of technology, that the present invention provides a significant advance over the prior art. The present invention will further allow for less stringent manufacturing tolerances, increased manufacturing flexibility, reduction and/or elimination of excessive load and/or damage to the pump tube during installation, and improved performance. These and additional features and advantages of the invention disclosed herein will be further understood from the following detailed disclosure of preferred embodiments.